subject was: RFI:Microphone for recording 360 degrees of sound
Our posts on not putting your mic on the ground was related to 360
degree ambient recordings. That should not have been interpreted to
mean don't ever put your mic on the ground.
Further examples of when to use ground recording would be appreciated
but here are a couple examples of when to use a mic on the ground.
1. The grouse recording I posted within the last month was recorded
on the ground. Setup was made as close to where the bird was
displaying and I was confident my recording would be made of these
very low frequencies at a close distance. By putting the mic on the
ground I improved the overall signal to noise ratio.
2. The mud flats recording I also posted within the last month was
made with the mic about 4" off the mud. This was a pot hole where
the targets were suppose to be standing in the mud. Once again set
to reduce ambient noise and pick up those targets in the mud. The
first UFO talked about in this post was best guessed as a Mallard
Duck in glide over the flats. The second UFO was likely a sonic boom
and still could have been those aliens kicking in the warp drive.
3. Ground hillside or bank recordings. The ground can be used to
make an omni mic directional or simply to minimize background noise
off in one direction.
4. Maximize bass frequencies within a sound? I don't have a good
example yet but could see it working in theory.
5. Give an illusion of a 10' cricket or 4' mosquito. I have some
great 6' killer flys that sound like they carry their prey off at the
speed of light.
6. Others?
Rich Peet
--- In Walter Knapp <>
wrote:
> Rich Peet wrote:
> > Doug? I thought you were the guy that recommended step ladders
for
> > better sound?
> >
> > Don't put your mic on the ground. At least carry a cable tie and
tie
> > it to the twig of a bush at 5'. The end result of putting the
mic on
> > the ground for bird song frequencies is to cut the range of your
mic
> > to about 30% of the distance compared to 5'.
>
> I definitely agree. In the 70's when I worked as a environmental
> consultant I did some informal tests with our calibrated sound
> measurement system because we had a job that involved sound
measurement
> in the woods.
>
> This was in fairly open woods in the Pacific NW. Underbrush was
about 4'
> high, above that height you could see quite a ways through the tree
trunks.
>
> The difference between 4' and 1' off the ground varied depending on
> sound source direction and cover. But it was rarely less than 5dBA
lower
> at 1', and sometimes the drop was as much as 15dBA. Laying the mic
on
> the ground gave even greater drop.
>
> I'd say get your mic at least as high as the underbrush if
possible.
> Above 4' I found less variation, even when the brush was higher
than that.
>
> BTW, I'm one of the ones experimenting with tall stands. My tall
stand
> will get a mic up to about 17'. The sound is different, I'll not
say
> better because that depends on what you want. Reverberation seems
to be
> less, the sound more open, clearer.
>
> Often when recording with the Telinga I'll hold it at arm's length
above
> my head for a slight improvement in range over head height.
>
> Walt
>
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